Try running two web servers behind a single IP address. For example you want to run your own email system with webmail and Nextcloud for file synchronisation.

Try running two web servers behind a single IP address. For example you want to run your own email system with webmail and Nextcloud for file synchronisation. You want to secure them both with TLS. You have a single static IPv4 address (if you are lucky, otherwise you have to use a dynamic DNS service. So you have two things that both want to use 443/tcp on the same "external" IP address. Options: * Put one of them on a non standard port eg 8443 - rubbish but works (unless the app assumes and enforces 443 - some do) * Put in a proxy, eg HA Proxy - cool! it can be used to fix up TLS crapness and get you that A+ score on the SSL labs test but it can be tricky to set up * Get more IPv4 address space - RLY (for most of the world)? * IPv6 - generally statically assigned and you have billions of globally routable addresses to play with NAT creates a limitation inbound - in general outbound is fine unless you want to use SIP n RTP or FTP, in which case you may have to become a network engineer unless your router's ALGs work out of the box, if it has them, if they work correctly, if they don't actually break things. NAT adds a lot of complexity but it has become the norm.